Why don't people upvote questions they answer?

Because some times the question is poorly written, lacking enough detail, or just plain lazy in nature (google has easy to grasp hits, RTFM), which do not necessarily mean I won't answer it.

I'm much more likely to upvote a question if it makes me think "oh, interesting", was very well written (logical flow, solid background, well formatted code samples, spat of self-deprecating humor, etc.)

Just because you know the (or more likely an) answer to a question doesn't necessarily make that question "useful and clear".

You only get 30 votes per day. I read a lot of posts each day. If I voted for everything that deserved it, I'd be out of votes by 9am. So I tend to reserve it for posts that I find are the most helpful. Sometimes they are questions, but more often it's an answer.

I also like to reserve my votes for things that are not only simply "right", especially about easier problems, but also especially insightful in some way, or provide good answers to more difficult problems. I like to think the rep people earn here was really earned, that it means something (even if in reality it probably doesn't).

For questions, I'll often give an upvote to someone who responds when I ask them for clarification.

Upvoting for answers makes sense: your answer is competing with other answers and upvotes is how the community "picks" the best answer.

Upvoting questions has no similar context. After all two Java questions don't relate to each other, vying to be picked as the best. It just doesn't make sense.

Plus, in SO, question askers are the consumers, answerers are the producers. Production is harder than consumption and thus deserves more reward, basically.

I do upvote questions on occasion, usually for one of two reasons:

• A total newb has asked a real quesiton. This is an almost automatic upvote for me to get them to the point where they can vote/comment/etc. Part of the need for this has been diminished by by changes allowing people to do this on questions they ask but still I want to get people asking real questions up there ASAP; and
• The question is truly outstanding, in terms of the value of its answers, the issues that it raises or the usefulness of the question. This is a truly subjective decision.

Answers are easy: tyou upvote the right/best ones.

Judging from my own limited personal experience (both looking for questions, asking questions and answering questions) - there seems to be a culture of non-upvoting on Stack Overflow as opposed to some other Stack Exchange sites.

For example, on TeX.SE it is much more likely to get a couple of upvotes for a reasonable, relatively-well-written question which applies to more than just yourself. You won't get that on SO. Now, people here might justify it in various ways:

• I don't think it's useful and clear enough.
• It may be useful for others, but not for me.
• I won't upvote unless [Insert some hard-to-meet condition here].
• Can't spare the change^H^H^H^H^H^H votes.

And these are, well, kind of valid reasons, I suppose, but I feel there's a lack of magnanimity on SO with respect to upvoting.

Edit: On second thought, I take that back. most of them are not really valid. Grrr!

I upvote questions that I found useful to me. If I have a problem and I find the solution on SO, the question and answer get an upvote.

I answer questions which aren't useful to me, because I already know the answer. I frequently look over the unanswered questions to see if I can help someone out, and I'll answer all the questions I can, but that doesn't mean those questions good or useful to me.

A lot of times I answer questions that I think the user could have solved on their own with minimal knowledge of google/bing. While I won't up-vote the question, I still like to help solve them for a few reasons:

• to help the user out, after all, that's why we're here, right?

• in some cases to suggest a better approach, since the problem the user is trying to solve might just be due to an unfortunate architecture decision (e.g. "how can I stop change data capture from killing my performance?"), or they may have already seem to have decided on the wrong solution (e.g. "how do I use dynamic SQL and cursors to do x?").

• also hopefully to install some good coding/naming practices compared to what they might find out there (or what they might have presented in the code in their question).

• a selfish reason: for my own practice, since I'm not in a position where I get to solve these kinds of problems anymore, and I kind of miss it sometimes.

I also don't up-vote questions when I have to pry and pry for enough information. "Doesn't work" and missing details about what has already been tried are up there, but most frequently I have to ask what version of SQL Server is being used. (As an aside, I wonder if it would be possible to enforce or at least suggest that the user pick a specific/minimum version for sql-server questions, if they've only tagged with sql-server - since solutions can be very different and much more efficient for 2005+ or 2008+. I think I know what my next feature request will be.)

Typically I up-vote questions that are challenging to solve or present a new problem that I haven't encountered before. I suspect that some people stay within their comfort zone. I do as well, to an extent - I stay in the SQL Server realm, but I do try to solve problems I don't have direct experience with. If I can already google the problem and come up with several solutions, it just isn't worth an up-vote IMHO, even if I do plan on posting an answer.

I upvote question I answer because they generally have no other answers, or have non-upvoted answers.

That way I increase the visibility of the question on the "Unanswered" tab, hoping to attract other answers challenging or completing mine.

Since most users might be unaware of that particular side effect (increase in visibility on a SO tab), they might associate upvote solely with the quality of the question (redaction, research, clarity, ...), which is a good criteria.
I only think it should not be the only criteria, especially for questions on narrow topics.

I almost always vote up questions I answer. It's foolish not to, because voting it up keeps the question on the front page, and if more users click on the question, more will see your answer, giving your answer more chance of being upvoted.

I upvote good questions, the same as good answers. Obvious? For instance, this question isn't that great so I haven't upvoted it. However, Stu gave a good answer to an obvious question, so I and others have upvoted that.

OTOH, questions are far more scarce than answers. Perhaps questions should count double.

I can't believe nobody has answered this honestly yet.

It's because people who answer questions in the first 2 minutes of a post are farming reputation by trying to be the first answer on as many questions as possible. They have no incentive to take the 2 seconds to click the "up" button because that doesn't give them more reputation.

It's the same reason why you see stub SO answers within literally seconds of a question going up, then subsequent edits in the following minutes actually answering the question. They get more upvotes for getting something up first, and there is no downside to throwing up a crap placeholder answer before actually filling it out.

I'm willing to bet if Stack Exchange enforced voting (or or down) before activating the answer text box we would see a ton more upvotes on questions, and the same number of answers.